This invention relates to glass fiber-elastomeric products, and more particularly to the treatment of glass fibers and compositions in the treatment of glass to facilitate the combination of glass fibers with elastomeric materials such as in the manufacture of glass fiber-reinforced elastomeric products.
The term "glass fibers,"as used herein, is intended to refer to and include (1) continuous fibers formed by rapid attenuation of hundreds of streams of molten glass and to strands formed when such continuous glass fiber filaments are gathered together as they are being formed; and to yarns and cords formed by plying and/or twisting a number of strands together, and to woven and non-woven fabrics which are formed of such glass fiber strands, yarns or cords, and (2) discontinuous fibers formed by high pressure steam, air or other suitable attenuating force directed onto multiple streams of molten glass issuing from a glass melting bushing or from an orifice containing spinner, and to yarns that are formed when such discontinuous fibers are gathered together to form a sliver which is drafted into a yarn; and to woven and nonwoven fabrics formed of such yarns of discontinuous fibers, and (3) combinations of such continuous and discontinuous fibers in strands, yarns, cords and fabrics formed thereof.
As used herein, the term "elastomer" is intended to mean and include natural rubber in the cured or uncured stage, vulcanized or unvulcanized stage, and synthetic organic elastomeric materials such as nitriles, acrylics and esters and terpolymers thereof with styrene and acrylonitriles, styrene and vinyl pyridine; and EPDM rubbers as represented by butadiene polymers and copolymers with monoolefins such as butadiene-styrene vinyl pyridine terpolymers, chloroprene, isoprene, neoprene, isobutyl rubber and the like elastomeric polymers and copolymers in their cured or uncured stages, and vulcanized or unvulcanized stages. Included also are the EPDM rubbers, such as formed by the interpolymerization of ethylene, an alpha-monoolefin having from 3-20 carbon atoms, such as propylene, and polyene, such as dicyclopentadiene, 1,4-hexadiene and preferably an alkylene or alkylidene norbornene, such as 5-alkylidene-2-norbornene and the like in which the alkylidene group numbers from 2-12 carbon atoms, and polysulfone rubbers.
It is now well known to combine glass fibers with elastomeric materials in the manufacture of glass fiber-reinforced elastomeric products, such as driving belts, timing belts, pneumatic tires, etc. One of the problems which has been encountered in such combinations of glass fibers with elastomeric products is the problem of securely anchoring the glass fiber surfaces to the elastomeric material in which the glass fibers are distributed. It is believed that this problem stems in part from the fact that the glass fibers are completely smooth, rod-like members and in part from the fact that the glass fiber surfaces are highly hydrophilic in nature, thereby resulting in the formation of a thin but tenacious film of water on the glass fiber surfaces which serves to destroy any bond, chemical or physical, which would otherwise be formed between the glass fiber surfaces and the elastomeric material with which the glass fibers are combined.
To minimize the problems of bonding the glass fiber surfaces to the elastomeric materials, it has been the practice in the manufacture of glass fiber-reinforced elastomeric products to make use of glass fibers in the form of individual glass fibers having a coating on the surfaces thereof to intertie the individual glass fibers to the elastomeric material in which the glass fibers are distributed, or preferably glass fibers in the form of yarns, cords, chopped strands or fabrics, hereinafter referred to as bundles, containing an impregnant therein which also serves to intertie the glass fiber bundles to the elastomeric material in which the bundles are distributed.
Various compositions may be used in the treatment of glass fibers, either as size compositions for application to the surfaces of individual glass fibers, or as impregnant compositions for impregnation of glass fiber bundles. Conventional size compositions are illustrated in U.S. Pat. No. 3,424,608 and are generally formed of a film-forming material, a wetting agent and a glass fiber lubricant. Most size compositions now in use are formulated to contain a glass fiber anchoring agent, preferably in the form of an organo silane, such as gamma-aminopropyltriethoxy silane or a Werner complex compound.
Impregnating compositions now in use are formulated to contain a resorcinol-aldehyde resin component and an elastomer component. Impregnating compositions are illustrated in U.S. Pat. Nos. 3,424,608 and 3,567,671, as well as numerous others. It has been the practice in the manufacture of glass fiber reinforced elastomeric products to first coat the individual glass fiber filaments with a size compositon embodying an organo silicon compound as an anchoring agent, and then impregnate a bundle of the sized fibers with an impregnating composition formulated of a resorcinol-aldehyde resin component and an elastomer component. The resulting bundle can then be combined with an elastomeric material in the manufacture of glass fiber-reinforced elastomeric products.
The size coating on the individual glass fibers is believed to improve the processing characteristics of the glass fibers without destroying their fibrous characteristics and to promote the bonding relationship between the elastomeric component of the impregnant. The impregnant is believed to intertie the impregnated bundle with the elastomeric material constituting the continuous phase with which the bundles are combined.
It has been proposed to modify the above described practice by eliminating one step of the sizing and impregnating technique. Such proposals most frequently suggest that the impregnating composition be applied directly to the individual glass fibers, preferably as they are formed, to form a coating thereon. However, it has been found that the bonding relationship between glass fibers treated in this manner and elastomeric materials is poor unless the impregnating composition is formulated to contain an organo silicon compound as an anchoring agent.
Such anchoring agents can be formulated with impregnating compositions of the type described above. However, the resulting composition is not completely stable because the highly acidic nature of the organo silicon compounds tends to cause coagulation of the latex containing the resorcinol-aldehyde resin and the elastomer.
It is therefore an object of the present invention to provide a composition for use in the treatment of glass fibers which contains a resorcinol-aldehyde resin component and an elastomer component which overcomes the foregoing disadvantages.
It is a more specific object of the present invention to provide a composition for use in the treatment of glass fibers to improve the bonding relationship between glass fibers and elastomeric materials in the manufacture of glass fiber reinforced elastomeric products in which a system of organo silicon compounds is formulated with a latex of a resorcinol-aldehyde resin and an elastomer without resulting in coagulation of the latex.